As a matter of fact, they are.
They are both instances where two consenting adults wish to get married and were denied access to those laws. Now one of those groups has finally managed to access them. There is not reason that the other should not also have the same access.
No as a matter of fact they are not.
They are indeed both instances where two consenting adults wish to get married and in each case a separate and distinct law prevents them from getting married.
When gay couples went to court for redress, they went to court for redress on their specific issue- exactly as the Lovings did when they went to court to argue that the law which said that they could not get married because of their race was unconstitutional.
When the Lovings won their case, it did not mean that inevitably that gay couples were constitutionally guaranteed a right to marriage.
What did happen was that gay couples- as the Lovings did- argued that their equal rights under the 14th Amendment were violated. States can deny people Constitutional rights- but States can only do so if they can provide a compelling and convincing argument to deny those rights- for example- denying convicted felons the right to own weapons.
States were never able to make a convincing argument as to why mixed race couples or gay couples should not be allowed to marry.
Can States make a convincing argument that marriage between two siblings should be illegal? If States can't- then they couldn't before Obergefell, if States can- then they can regardless of Obergefell.